Shivering

This morning at work I was standing talking with someone and my arm started shaking so much it was like I was shivering in the cold. It's the first time that happened without any assignable cause.

I'm finding that if I'm cold, my right arm will shiver much more and much sooner than my left arm. If I'm exerting myself, it's the same sort of thing, but today was the first time my arm shook like that with no apparent cause.